Auxiliary control device



Jan. 4, 1966 J. N. COATS 3,226,998

AUXILIARY CONTROL DEVICE Filed NOV. 24, 1961 95 Fig. 4

IIVVEIVTOR JOHN N. COATS B) BUCKHORN, CHEATHAM 8 BLORE ATTORNEYS United States Patent 3,226,998 AUXILIARY CQNTROL DEVICE John N. Coats, 2010 SW. Wernhly Park Drive, Lake Oswego, Oreg. Filed Nov. 24, 1961, Ser. No. 154,435 Claims. (Ci. 74-526) This invention relates to auxiliary control devices to supplement existing control means.

In some control systems, there is a danger that if the existing control means fails, the mechanism being controlled will assume an undesired condition of operation. For instance, in industrial furnaces with forced draft blowers, there is a control means to vary the output of the blower in accordance with the temperature in the furnace and/or the temperature of the exhaust gases from the furnace. Should the control means fail, the blower would be deenergized to allow the furnace to overheat.

It is a main object of the present invention to provide a simple and effective auxiliary control device or supervising means to supervise the existing control means or device to prevent the mechanism or operating means being controlled from assuming an undesired operating condition in the event the existing control means fails.

In many existing control means there is a part, such as a lever, that is moved through a range of movement to give the desired variations in the operation of the controlled mechanism or operating means.

It is an important object of the invention to provide an over the overall range to enable movement of such control means part through its overall range provided said control device is reset. Thus, if the existing control means fails, the auxiliary control device will hold the control means part at or close to its last position to prevent undesirable operation of the mechanism being controlled.

Another object is to provide an auxiliary control device as just described above in which there are manual means for effecting resetting of the limited range contrivance of the device.

A further object is to provide an auxiliary control device as just described having a warning system to indicate when resetting is due.

Various other objects of the invention will be apparent from the following description taken in connection with the accompanying drawings wherein:

FIG. 1 is a somewhat diagrammatic view of an entire system embodying the concepts of the present invention;

FIG. 2 is a vertical sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is a view of a portion of FIG. 1 showing different positions of certain parts; and

PEG. 4 is a diagram of the alarm circuit of the present invention.

Referring to FIG. 1, the mechanism or operating means being controlled comprises a furnace which includes a furnace box 11 having a blower 13 providing forced draft for the box. There is a conventional control box 15 for the blower operated by a link 17. The link is pivotally connected at 19 to an end of a control lever 21. The other end of the lever is fixed to a shaft 23, which as diagrammatically indicated, is journaled in a main controller 25.

The above construction, including the controller 25, is of conventional form. For convenience, the furnace is shown on a smaller scale than the controller. The controller is actuated by one or more heat sensing coni in or on the furnace.

'ice

trivances (not shown) of conventional form and located As the temperature rises, the need for more air is indicated by the sensing contrivances, and the controller actuates the control box 15 and thus the blower 13 accordingly.

However, should the controller not perform as expected, because of failures in the controller or its sensing means or because of failure of the power supply to the controller, there is considerable danger that the controller will cut off or greatly diminish the supply of air to the furnace, causing it to overheat to damage it and/ or mechanisms or parts associated with it. This is obviously an undesirable operating condition. For convenience hereinafter, the controller 25 may be referred to as the existing control means.

To prevent the above described undesirable operating conditions from occurring, an auxiliary or supervisory control device is provided. It comprises a stop carrier 31 of plate like form (FIGS. 1 and 2) freely pivotally mounted intermediate its length on the shaft 23 rearwardly of the lever 21 (FIG. 2). The carrier is normally held stationary by a closed circuit piston and cylinder unit generally indicated at 33, to be presently described. The stop carrier has a widened end portion 34 which supports a pair of stop blocks 35 and 37 which are disposed one on either side of the lever 21 and are spaced apart a distance substantially greater than the width of the lever 21. Thus the lever 21 has a limited range of movement between the stop blocks 35 and 37.

The piston and cylinder unit 33 comprises a cylinder 41pivotally mounted at 43 on a pair of spaced standards 45. The cylinder 41 has a piston 47 equipped with a piston rod 49 that passes through the piston and out both ends of the cylinder and is pivotally connected at 51 to the end of the carrier 31 remote from the stop blocks 35 and 37. Thus the pivot 51 is spaced from and disposed on one side of the shaft 23, while the stop blocks 35 and 37 are spaced from and disposed on the other side of the shaft 23.

A conduit 53 connects the opposite ends of the cylinder 41, but flow through the conduit is controlled by held stationary. However, when the valve 55 is opened,

the piston 41 can move in either direction.

Mounted on each stop block is a single acting cylinder 61. Each cylinder has a piston 63 (shown for the upper cylinder) and each piston has a rod 65 slidahly extending through a hole formed in the associated stop block. A compression spring 67 in each cylinder urges the associated piston to assume a position remote from the lever 21. The spring 67 is preferably of lesser diameter than the piston and has its outer end recessed in the piston to enable the piston to bottom against the inner end wall of the cylinder.

A suitable conduit 69 leads from the free end of each cylinder and both conduits are connected (FIG. 2) to a control valve 71 which is connected to a supply 73. The valve 71 can be operated to supply fluid. under pressure to the cylinders or to isolate the supply from the cylinders and vent the cylinders to a reservoir, in case liquid is used, or to the atmosphere in case air is used.

The rods 65 are so dimensioned lengthwise that when their pistons are in their full inner positions, the inner.

ends of the rods are in simultaneous engagement with or in contiguous relation to the lever 21. Thus the cylinder units on the stop blocks function as a centering means for centering the lever 21 between the stop blocks and relative to the carrier 31.

Operation The operation of the parts so far described is as follows: Normally the valve 55 is closed and the valve 71 is in its exhaust position so that the carrier 31 is held stationary and the piston rods 65 are retracted. The controller 25 has control over the lever 21 and can move the lever within the limited range permitted by the stop blocks 35 and 37. Should the controller fail, the lever 21 cannot move beyond the stop blocks and thus the supply of air to the furnace by the blower 13 is maintained.

However, the overall or full range of movement of the lever 21 is indicated in full and broken lines in FIG. 3, and the lever is permitted to assume such positions, under the supervision of the auxiliary control device. This works as follows. When the lever comes up against or comes close to a stop block, such as shown in broken lines in FIG. 1, the valve 55 is opened by the attendant to free the carrier 31, and then the valve 71 is operated to connect the supply 73 to the cylinders 61 to project the piston rods 65. The upper rod will exert a downward force on the lever 21, but since the lever is frictionally held in place (by a friction drive in the controller 25) and the carrier 31 is free to move, the equal and opposite force by the rod 65 on the stop block 35 turns the carrier 31 in a counterclockwise direction until the lever 21 is centered relative to the stop blocks and carrier. Then the valve 55 is closed to hold the carrier in its adjusted position, and the valve 71 is operated to exhaust fluid from the stop cylinders 61 to enable the springs 67 to retract the rods 65 to free the lever 21 for movement under the control of the controller 25. This operation can be repeated as often as desired, although it is pointed out that in a control system of the type disclosed, only occasional relocation of the carrier 31 is required because the position of the lever 21 does not fluctuate Widely over a limited period of time.

Alarm system In most installations, it is not desirable to require a maintenance man to keep checking the position of the lever 21 to ascertain when resetting the carrier 31 is necessary. Therefore, an alarm system is provided to give both a visual and an audible indication when resetting is required.

The alarm system includes a pair of microswitches 81 mounted on extensions 83 of the carrier 31 and having spring biased actuating fingers 85 located so as to be engaged by the lever 21 just before the lever engages the stop blocks 35 and 37. The switches are shown in FIG. 4 incorporated in a control circuit. The upper switch 81, when closed serves to energize the lamp 87 and a solenoid switch 89, the latter serving to energize a buzzer 91.

When the lower switch 81 is closed it serves to energize the lamp 93 and a solenoid switch 95, the latter causing energization of the buzzer 91.

The control circuit also preferably includes a switch 97 to enable remote energization of the control valve 71, and a switch 99 to enable remote energization of the control valve 55.

In the claims, the auxiliary or supervising control arrangement may be referred to as an auxiliary control means or device or as a supervising means or device. The controller 25 and the associated mechanism including the lever 21 may be referred to as a control device. The means ultimately controlled by the overall arrangement, namely the furnace 11, may be referred to as a mechanism or as an ope-rating means or device.

Having described the invention in what is considered to be the preferred embodiment thereof, it is desired that it be understood that the invention is not to be limited other than by the provisions of the following claims.

I claim:

1. In combination with a control device which controls a mechanism by way of a lever movable by the control device through a predetermined overall range of movement, where inoperativeness of the control device might allow the mechanism to assume an undesired condition of operation.

the improvement comprising auxiliary control means independent of said control device to releasably limit said lever to a range of movement less than said overall range, so that inoperativeness of said control device cannot have the undesirable action above mentioned, said auxiliary control means comprising: a pair of stops disposed one on either side of said lever in spaced relation thereto, a carrier for said stops, means normally holding said carrier stationary but operable when actuated to release said carrier for free movement, and means operable when actuated for moving said free carrier to a position where said stops are centered relative to said lever so that when said lever assumes an extreme position relative to said stops, a new limited range of movement for the lever can be established without loss of control over the lever by said auxiliary control means. 2. In combination with a control device which controls a mechanism by way of a part movable by the control devise through a predetermined overall range of movement, wherein inoperativeness of the control devise might allow the mechanism to assume an undesired condition of operation,

the improvement comprising auxiliary control means independent of said control device to releasably limit said part to a range of movement less than said overall range, so that inoperativeness of said cOntrOl device cannot have the undesirable action above mentioned, said auxiliary control means comprising: a pair of stops disposed one on either side of said part in space relation thereto, a carrier for said stops, means normally holding said carrier stationary but operable when actuated to release said carrier for free movement, and means operable when actuated for moving said free carrier to a position where said stops are centered relative to said part so that when said part assumes an extreme position relative to said stops, a new limited range of movement for the part can be established without loss of control over the part by said auxiliary control means. 3. In combination with a control device which controls a mechanism by way of a lever movable by the control device through a predetermined overall range of movement, wherein inoperativeness of the control device might allow the mechanism to assume an undesired condition of operation,

the improvement comprising auxiliary control means independent of said control device to releasably limit said lever to a range of movement less than said overall range, so that inoperativeness of said control device cannot have the undesirable action above mentioned, said auxiliary control means comprising: stop means for said lever providing for a limited range of movement therefor, a carrier for said stop means, means normally holding said carrier stationary but operable when actuated to release said carrier for free movement, and means operable when actuated for moving said free carrier to a position where said stop means are centered relative to said lever so that when said lever assumes an extreme position relative to said stop means, a new limited range of movement for the lever can be established without loss of control over the lever by said auxiliary control means.

4. In combination with a control device which controls a mechanism by way of a part movable by the control device through a predetermined overall range of movement, wherein inoperativeness of the control device might allow the machanism to assume an undesired condition of operation,

the improvement comprising auxiliary control means independent of said control device to releasably limit said part to a range of movement less than said overall range, so that inoperativeness of said control device cannot have the undesirable action above mentioned, said auxiliary control means comprising: stop means for said part providing for a limited range of movement therefor, a carrier for said stop means, means normally holding said carrier stationary but operable when actuated to release said carrier for free movement, and means operable when actuated for moving said free carrier to a position where said stop means are centered relative to said part so that when said part assumes an extreme position relative to said stop means, a new limited range of movement for the part can be established without loss of control over the part by said auxiliary control means. 5. In combination with a control device which controls a mechanism by way of a lever movable by the control device through a predetermined overall range of movement, wherein inoperativeness of the control device might allow the mechanism to assume an undesired condition of operation,

the improvement comprising auxiliary control means independent of said control device to releasably limit said lever to a range of movement less than said overall range, so that inoperativeness of said control device cannot have the undesirable action above mentioned, said auxiliary control means comprising: a pair of stops disposed one on either side of said lever in spaced relation thereto, a carrier for said stops, means normally holding said carrier stationary but operable when actuated to release said carrier for free movement, and means operable when actuated for moving said free carrier to a predetermined intermediate position relative to said lever so that when said lever assumes an extreme position relative to said stops, a new limited range of movement for the lever can be established without loss of control over the lever by said auxiliary control means. 6. In combination with a control device which controls a mechanism by way of a part movable by the control device through a predetermined overall range of movement, wherein inoperativeness of the control device might allow the mechanism to assume an undesired condition of operation.

the improvement comprising auxiliary control means independent of said control device to releasably limit said part to a range of movement less than said overall range, so that inoperativeness of said control device cannot have the undesirable action above mentioned, said auxiliary control means comprising: a pair of stops disposed one on either side of said part in spaced relation thereto, a carrier for said stops, means normally holding said carrier stationary but operable when actuated to release said carrier for free movement, and means operable when actuated for moving said free carrier to a predetermined intermediate position relative to said part so that when said part assumes an extreme position relative to said stops, at new limited range of movement for the part can be established without loss of control over the part by said auxiliary control means.

7. A supervising means for supervising the operation of a control device, wherein said control device normally controls the operation of an operating means in response to certain operating conditions of said operating means, and wherein said operating means can be damaged if said control device malfunctions and effects operation of said operating means in a substantially different way from that demanded by its operating conditions, and wherein said control device has a lever mounted for pivoting movement through an overall range of movement in effecting the overall control of said operating means, but which lever is normally movable through only a portion of such range, and wherein said lever resists movement it movement of such lever is urged by forces imparted thereto other than by said control device,

said supervising means including,

a pair of stops disposed one on either side of said lever in space relation thereto,

a carrier for said stops mounted for pivotal movement about the same axis as said lever,

a liquid filled piston and cylinder unit connected to said carrier in spaced relation to the said axis,

releasable means precluding the discharge of liquid from either end of said piston and cylinder unit whereby to hold said carrier in a stationary position, whereby malfunctioning of said control device cannot move said lever beyond the confines of said stops, and thus operation of said operating means in a manner which might be damaging is precluded,

piston and cylinder means on said carrier operable when actuated to urge said lever to assume a centered position relative to said stops,

means to inactivate said releasable means to enable free movement of said carrier,

and means to cause actuation of said piston and cylinder means to tend to move said lever, but instead to cause said carrier to assume a new position because of the resistance to movement by said lever, whereafter said releasable means can be reactivated and said piston and cylinder means deactuated to establish a new limited range of movement of said lever relative to said stops.

8. In combination with a control device which normally controls the operation of an operating means in response to certain operating conditions of said operating means, and wherein said operating means can be damaged it said control device malfunctions and effects operation or" said operating means in a substantially different way from that demanded by its operating conditions, and wherein said control device has a lever mounted for pivoting movement through an overall range of movement in effecting the overall control of said operating means, but which lever is normally movable through only a portion of such range,

a supervising means for supervising the operation of said control device, wherein said lever resists move ment if movement of such lever is urged by forces imparted thereto other than by said control device,

said supervising means including,

a pair of stops disposed one on either side of said lever in spaced relation thereto,

a carrier for said stops mounted for pivotal movement about the same axis as said lever,

a liquid filled piston and cylinder unit connected to said carrier in spaced relation to the said axis,

releasable means precluding the discharge of liquid from either end of said piston and cylinder unit whereby to hold said carrier in a stationary position, whereby malfunctioning of said control device cannot move said lever beyond the confines of said stops and thus operation of said operating means in a manner which might be damaging is precluded,

piston and cylinder means on said carrier operable means to inactivate said releasable means to enable free movement of said carrier,

and means to cause actuation of said piston and cylinder means to tend to move said lever, but instead to cause said carrier to assume a new position because of the resistance to movement by said lever, whereafter said releasable means can be reactivated and said piston and cylinder means deactuated to establish a new limited range of movement of said lever relative to said stops.

9. A supervising means for supervising the operation of a control device, wherein said control device normally controls the operation of an operating means in response to certain operating conditions of said operating means, and wherein said operating means can be damaged it said control device malfunctions and effects operation of said operating means in a substantially different Way from that demanded by its operating conditions, and wherein said control device has a member mounted for movement through an overall range of movement in effecting the overall control of said operating means, but which member is normally movable through only a portion of such range, and wherein said member resists movement if movement of such member is urged by forces imparted thereto other than by said control device,

said supervising means including,

a pair of stops disposed one on either side of said member in spaced relation thereto,

a carrier for said stops mounted for movement to vary the position of said stops relative to said member,

a liquid filled piston and cylinder unit connected to said carrier, releasable means precluding the discharge of liquid from either end of said piston and cylinder unit whereby to hold said carrier in a stationary position, whereby malfunctioning of said control device cannot move said member beyond the confines of said stops and thus operation of said operating means in a manner which might be damaging is precluded,

piston and cylinder means on said carrier operable when actuated to urge said member to assume a centered position relative to said stops,

means to inactivate said releasable means to enable free movement of said carrier,

and means to cause actuation of said piston and cylinder means to tend to move said member, but instead to cause said carrier to assume a new position because the resistance to movement by said member, Whereafter said releasable means can be reactivated and said piston and cylinder means deactuated to establish a new limited range of movement of said member relative to said stops.

10. In combination with a control device which normally controls the operation of an operating means in response to certain operating conditions of said operating means, and wherein said operating means can be damaged it said control device malfunctions and effects operation of said operating means in a substantially different way from' that demanded by its operating conditions, and wherein said control device has a member mounted for movement through an overall range of movement in effooting the overall control of said operating means, but which member is normally movable through only a portion of such range,

a supervising means for supervising the operation of said control device wherein said member resists movement it movement of such member is urged by forces imparted thereto other than by said control device,

said supervising means including,

a pair of stops disposed one on either side of said member in spaced relation thereto,

a carrier for said stops mounted for movement to vary the position of said stops relative to said member,

a liquid filled piston and cylinder unit connected to said carrier,

releasable means precluding the discharge of liquid from either end of said piston and cylinder unit whereby to hold said carrier in a stationary position, whereby malfunctioning of said control device cannot move said member beyond the confines of said stops and thus operation of said operating means in a manner which might be damaging is precluded,

piston and cylinder means on said carrier operable when actuated to urge said member to assume a centered position relative to said stops,

means to inactivate said releasable means to enable free movement of said carrier,

and means to cause actuation of said piston and cylinder means to tend to move said member, but instead to cause said carrier to assume a new position because of the resistance to movement by said member, whereafter said releasable means can be reactivated and said piston and cylinder means deactuated to establish a new limited range of movement of said member relative to said stops.

References Cited by the Examiner UNITED STATES PATENTS 1,831,077 11/1931 Newell 236-16 X 1,926,680 9/1933 Kronmiller 23616 2,162,174 6/1939 Jones 18082 X 2,373,130 4/1945 Malone 2369 2,472,176 6/1949 Stern 74-526 3,004,525 10/1961 Emain 74-526 3,130,599 4/1964 Haas 74526 FOREIGN PATENTS 377,532 7/1932 Great Britain.

BROUGHTON G. DURHAM, Primary Examiner. 

1. IN COMBINATION WITH A CONTROL DEVICE WHICH CONTROLS A MECHANISM BY WAY OF A LEVER MOVABLE BY THE CONTROL DEVICE THROUGH A PREDETERMINED OVERALL RANGE OF MOVEMENT, WHERE INOPERATIVENESS OF THE CONTROL DEVICE MIGHT ALLOW THE MECHANISM TO ASSUME AN UNDESIRED CONDITION OF OPERATION. THE IMPROVEMENT COMPRISING AUXILIARY CONTROL MEANS INDEPENDENT OF SAID CONTROL DEVICE TO RELEASABLY LIMIT SAID LEVER TO A RANGE OF MOVEMENT LESS THAN SAID OVERALL RANGE, SO THAT INOPERATIVENESS OF SAID CONTROL DEVICE CONNOT HAVE THE UNDESIRABLE ACTION ABOVE MENTIONED, SAID AUXILIARY CONTROL MEANS COMPRISING: A PAIR OF STOPS DISPOSED ONE ON EITHER SIDE OF SAID LEVER IN SPACED RELATION THERETO, A CARRIER FOR SAID STOPS, MEANS NORMALLY HOLDING SAID CARRIER STATIONARY BUT OPERABLE WHEN ACTUATED TO RELEASE SAID CARRIER FOR FREE MOVEMENT, AND MEANS OPERABLE WHEN ACTUATED FOR MOVING SAID FREE CARRIER TO A POSITION WHERE SAID STOPS ARE CENTERED RELATIVE TO SAID LEVER SO THAT WHEN SAID LEVER ASSUMES AN EXTREME POSITION RELATIVE TO SAID STOPS, A NEW LIMITED RANGE OF MOVEMENT FOR THE LEVER CAN BE ESTABLISHED WITHOUT LOSS OF CONTROL OVER THE LEVER BY SAID AUXILIARY CONTROL MEANS. 